(1) Field of the Invention
The present process relates generally to treated fabrics having a substantially increased degree of lightfastness as compared with untreated fabrics and, more particularly, to a method of improving the lightfastness of dyed Cordura fabric by treating the fabric with an aqueous solution containing a cinnamate ester.
(2) Description of the Prior Art
The automotive industry requires an upholstery material which can resist decoloration over time. Normally, fabric is dyed with an appropriate dye and then treated with a chemical treating agent to improve the lightfastness of the upholstery material. However, with the need for higher and higher quality products, the automotive industry is demanding improved upholstery materials. Thus, there is a need for a process which produces an upholstery material having a substantial increase in lightfastness.
Lightfastness refers to the resistance of a material to change in its color characteristics as a result of exposure to sunlight or an artificial light source. It is a special case (a subset) of the broader concept of colorfastness. Colorfastness refers to the resistance of a material to change in its color characteristics, to transfer of its colorants to adjacent materials, or both, as a result of exposure to any real or simulated environment encountered during processing, storage, use or testing of the material.
U.S. Pat. No. 5,000,945 (Kobayashi et al) relates to the use of para-methoxy cinnamic acid compounds as UV absorbers. The compounds can be incorporated into fibers, paints and resins. The patent does not disclose the use of cinnamate ester compounds as modifiers for improving the lightfastness of Cordura.TM. (nylon) fabrics.
U.S. Pat. No. 4,783,142 (Mutzhas) relates to the use of cinnamic acid compounds as UV absorbers. The compounds can be incorporated in coatings for shades, awnings, tents and the like. The patent does not disclose the use of cinnamate ester solutions to improve the lightfastness of Cordura.TM. fabrics.
All of the above patents are incorporated herein by reference in their entirety.
Fabrics useful as upholstery material in the automotive industry are Cordura.TM. (nylon) fabric and polyester fabric. The Cordura fabric is preferred because it is more durable and can be more easily installed. The Cordura fabric is dyed with an acid dye or a pre-metallized acid dye. The polyester fabric is dyed with a disperse dye.
Typical acid dyed fabrics have a lightfastness according to the AATCC standard testing methods of about 60 to 80 hours. Fabrics dyed with pre-metallized acid dyes (metal complexes) have increased lightfastness, but even these fabrics show appreciable loss of color after about 150 to 200 hours of testing. Color loss in the fabrics is due primarily to harmful effects of ultraviolet (UV) radiation. Although the limits of the spectral range of UV radiation are not well defined, the following range is commonly accepted:
UV-A 315 to 400 nm. PA1 UV-B 280 to 315 nm. PA1 UV-C 200 to 280 nm. PA1 (1) 16A-Carbon Arc Lamp, Continuous Light; PA1 (2) 16-C-Daylight; PA1 (3) 16D-Carbon Arc Lamp, Alternate Light and Darkness; PA1 (4) 16E-Water-Cooled Xenon-Arc Lamp, Continuous Light; PA1 (5) 16F-Water-Cooled Xenon Arc Lamp, Alternate Light and Darkness; PA1 (6) 16G-Colorfastness to Light Determination of Fastness above L-7.
The radiation falling within the range 315 to 400 nm (nanometers) appears to be the most harmful to the lightfastness of dyed fabrics.
Acid dyes are a class of water-soluble anionic dyes whose original members all had one or more sulfonic or carboxylic acid groups. Examples of acid dyes are azo compounds, anthraquinones, triarylmethanes, azines, xanthenes, ketone imines, nitro compounds, nitroso compounds and quinolines. These acid dyes can be applied to such materials as nylon, wool, silk, modified acrylics and leather.
Specific examples of acid dyes are CI Acid Green I (nitroso), CI Disperse Yellow 42 (Nitro), CI Acid Blue 116 (disazo), CI Direct Black 78 (trisazo), CI Acid Brown 120 (polyazo), CI Acid Green 3 (triarylmethane), CI Acid Yellow 5 (quinoline), CI Acid Blue 121 (azine), CI Acid Yellow 73 (xanthene), CI Disperse Red (azo), CI Blue I (indigoid), CI Direct Blue 986 (phthalocyanine).
Dyes which have been metallized by the dye manufacturer prior to use by the dyer are called "premetallized dyes". Two types of premetallized dyes are the 1:1 complexes and the 2:1 complexes. The ratios refer to the number of ligand-to-metal bonds in the complex. Premetallized dyes most commonly refer to metal complexes of certain o,o'-dihydroxyazo,o-carboxy-o'-hydroxazo,o-amino-o-hydroxazo, acrylazosalicylic acid and formazan compounds.
The premetallized dyes are used to dye substrates such as wool and nylon. Examples of premetallized acid dyes are acid Black 52 (monoazo), Acid Black 63 (monoazo), Irgalan Brown Violet DL (bis-azo, 2:1 chromium complex), Neolan Blue 2G (monazo, 1:1 chromium complex), Neolan Yellow GR (mono-azo, 1:1 chromium complex), Irgalan Brown Violet DL (bis-azo: 2:1 chromium complex), and CI Acid Black 180 (formazan-type, 2:1 cobalt complex).
Thus, there remains a need for a new and improved upholstery materials produced by a process which produces an upholstery material having a substantial increase in lightfastness over conventional dyes and treatments. It has been discovered that the harmful effects of UV radiation, especially UV-A radiation, on the lightfastness of dyed fabrics can be substantially reduced by the present invention.